Info on Dual-Channel

Discussion in 'Links' started by Twinke Masta, Dec 30, 2003.

  1. Twinke Masta

    Twinke Masta Guest

    I have compiled this for those interested in running Dual-Channel in their system or those who wish to learn more about the architecture…

    Dual Channel’s importance and how it’s affected the CPU industry…

    Speedy CPUs grab most of the headlines, but as processors get faster, they put more pressure on other, less prominent parts of PC architecture to keep pace. That's why perhaps this year's biggest desktop technology trend is the move to higher-bandwidth memory architectures, specifically, to system chipsets with dual-channel memory controllers.

    The appetite gap even affects relatively high-end chipsets like Intel's 845PE, which supports the latest Pentium 4 chips and Hyper-Threading technology, but is limited to the 333MHz memory speed of DDR333 (a.k.a. PC2700). The latter type of memory is a great match for a 333MHz-bus Athlon XP, but pairing it with a 533MHz-bus Pentium 4 is like using a Porsche to drive in city traffic.

    Dual-Channel Memory Designs

    Right now, there are two different strategies employed in dual-channel memory controllers, with the first being a platform with two independent channels in hardware. This is the format of nVidia's nForce and nForce2 chipsets for AMD Athlon XP systems, where each memory bank has its own memory channel and an arbiter distributes the load between them and plays traffic cop for incoming data.

    This has the benefit of high actual memory bandwidth, but comes at the cost of some system overhead or latency associated with the arbiter (a matter addressed or greatly reduced by the nForce2), along with greater limitations on installed memory. With the nForce2, for instance, sticking with two memory modules is the best option for full dual-channel performance and stability.

    The second strategy is to actually create a wider memory channel, thereby "doubling up" on standard DDR's 64-bit data paths. This is common of Intel dual-channel memory controllers. In the case of the E7205 workstation chipset (diagrammed below), each pair of installed modules acts as a 128-bit dual-channel memory module, which can transfer twice as much data as a single-channel solution, with no need for an arbiter. Depending on the application, this solution may not be as flexible as two hardware channels, and it does require an innovative chipset design to handle the 128-bit incoming data streams.

    [​IMG]

    There are also hardware limitations placed on dual-channel memory platforms, such as maintaining consistency between modules and how they are installed. Install memory modules incorrectly or mix types and speeds, and the system will either hang (i850E) or downshift to single-channel operation (E7205, nForce2). These are basic rules placed on the platform to ensure consistency and keep user errors to a minimum.

    How to install Dual-Channel…

    Well if you have a motherboard that supports dual channel, such as i875P or nForce 2, then you may have slots on your motherboard that are black and blue. If you have an Intel Board, then there usually should be 4 ramslots, 2 close together then a large space then another 2 close together. Of these ramslot pairs, there should be one blue and one black in a pair. When considering Dual-Channel, you want to make sure you put the matched pair in one pair slots ( example both sticks are in black slots or both in blue) instead of one in one pair slot and one next to it in the other, if you do put it wrongly the result will be like a regular ram and you won’t get the Dual-Channel boost in performance. So the basic concept is to put both matched paris in teh same colored slots. If you have 4 sticks of the same ram you may put them all in. Notice in the picture below of an ASUS P4P800 Deluxe i865PE with Dual-Channel Support, there are paired ramslots, and they have diferrent colors.

    [​IMG]

    AMD, however, can only utilize one colored pair of these ramslots for Dual-Channel, as seen here in the Picture of an ASUS A7N8X-E Deluxe nForce 2 Ultra.

    [​IMG]

    Notice there is only one pair of close ramslots, only that pair maybe used for Dual-Channel. Dual-Channel outputs a much larger performance difference than AMD system do.

    Select correct RAM for your Dual-Channel System.

    Well when you buy ram for your Motherboard’s Dual-Channel Capabilities you always have to buy a similar set or exact pair of ram preferred. You don’t have to have the exact same ram, but they must be the SAME speed (ex: both are PC-3200), both have to be the same size (ex: both are 512mb), both have to have the same configuration (ex: both are 64x64), these are required to run DC. But the most recommended is that both ram have the Same CAS timing as well (ex: both are 2.5 CAS) for optimal overclockability and stability of the complete system. When you buy ram, it is also recommended to buy the same company manufactured RAM (ex: both sticks are from Kingston or OCZ). Also remember that the best Dual-Channel is achieved from a memory kit, such as a 1024mb memory kit, the kit will come with 2x512mb sticks that are exactly the same.
     
    Last edited by a moderator: Dec 31, 2003
  2. ceesay

    ceesay Guest

    thx 4 the info...:)
     
  3. Twinke Masta

    Twinke Masta Guest

  4. Grov

    Grov Guest

    If you could make it like half the size, im sure it would be more helpful, theres just to much info.
     

  5. Twinke Masta

    Twinke Masta Guest

    i'll get on it right away...thanks grov ;)
     
  6. Twinke Masta

    Twinke Masta Guest

  7. gerrard17

    gerrard17 Member Guru

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    thanx for the info, I've got the abit Ic7 max 3 mobo and 2x 512mb pc4000 xms ddr ram, in slot 1 + 3 ....just built it

    is this right ??? - how do I know of its runnin dual channel ???
     
  8. Wicky

    Wicky Maha Guru

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    If you replace every occurence of the word "dual-channel" with "RAID", and "memory" with "harddisc", then we can save a lot of space for explaning a similar technology, used for doubling the transfer-speed of harddrives :)

    Wicky
     
  9. Twinke Masta

    Twinke Masta Guest

    yep if they in the same colored slots, then they are running in dual-channel [​IMG]
    notice the dark blue and light blue, if the ram are in same colored slots they are runnin in dual-channel mode...
     
  10. Twinke Masta

    Twinke Masta Guest

    lol it would apply for RAID lol, j/k :D
     

  11. gerrard17

    gerrard17 Member Guru

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    GPU:
    2x XFX Nvidia 7800GTX
    is there any benefit to having 2gb of ram rather than 1 ??

    I'm running at stock speeds at the moment, haven't experienced problems or anything, I'm just greedy really...(and have some £££ left)
     
  12. Twinke Masta

    Twinke Masta Guest

    as of right now 2gb of ram is kind of overkill, i gb of PC-4000 is wicked fast in dual-Channel mode as you probably already know PC-4000 = 500 mhz DDR or 1000 mhz Dual-channel and to take advantage of that, you might wanna overclock your bus speed to 1000 mhz from 800 mhz, your BSF right now is 800 mhz or 200 mhz x4 becuase pentium 4 has their FSB quad pumped, and you have a 3.2 because its at 16 multiplier x 200fsb wich outputs a 3200 mhz CPU, and if you can up that fsb a little higher your system will be overall faster since 200 mhz of the memory is just been wasted...
     
  13. gerrard17

    gerrard17 Member Guru

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    GPU:
    2x XFX Nvidia 7800GTX
    I've no idea about the overclocking stuff, how to do it etc.....

    where do I start, how do I know if its too hot etc????
     
  14. Twinke Masta

    Twinke Masta Guest

    if you don't know then it will take a while for you to learn...

    i'll PM you sometimes ok ;)
     
  15. NewMachineIII

    NewMachineIII Master Guru

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    Dual Info...

    TM....bless ya lad....ye has open my eyes to the light...AMEN!!!

    My system...is now a 'duet'...LOL
     
    Last edited: Jan 23, 2004

  16. six

    six Master Guru

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    Oh man, I hope I haven't screwed up, but I just ordered 1 pair of crucial 512 sticks of ddr400. But I just read in TM's post that it's best to buy a kit. I kinda figured this but I didn't think there was really a difference. I assume the kits contain pairs that are more perfectly matched (?)
     
  17. WildStyle

    WildStyle Ancient Guru

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    Dual channel matched kits are only really needed if you are overclocking heavily, it helps to make sure that one stick doesnt overclock more than the other. What you ordered will be fine I should think. :) Don' worry about it.
     
  18. Kermit_the_frog

    Kermit_the_frog Master Guru

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    I have 2 mobos that run in duel channel configs one is an MSI K7GN2 and one is Gigabyte G7NNXP , the MSI has 3 dimms I run #1 128mb #2 256mb and #3 128mb this works and runs duel channel , I ran the Giga which has 4 slots 4x 256 and that works also, only draw back was overclocking on the Giga it did not like all 4 dimms in use , I tried 3x256 and I was back at 210fsb and in duel also with 3 slots in use , I now run the Giga at #1 256mb #2 512mb and #3 256 for total 1 Gig in duel channel , so you can use all 3 slots of even 4 slots and still have duel channel working :)
     
  19. Tom F

    Tom F Ancient Guru

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    I hvae a few questions about Dual channel.

    1) Both of my pcs run on These motherboards. I dunno which slots to use for dual channel. At the moment, i am using the outer two, with the middle one empty. Is this right?

    2) What dort of difference does it make?

    3) Will it work Dual Channel with 3 sticks of RAM?
     
  20. Kermit_the_frog

    Kermit_the_frog Master Guru

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    Read my post above you see the MSI has all 3 in use and works duel channel

    Its faster all around but you are much better off when your CPU and RAM run at 100% speed ratio or 1:1

    Plus on the Nvidia boards the tras should be set something like 9 - 3 - 3 - 3

    not 6 - 3 - 3 - 3 even 11 - 3 - 3 - 3 might be faster for you depends on setups but the old school of 6 - 3 - 3 - 3 is slower on duel channel boards
    now if you have good ram you could run something like 11 - 2 - 2 - 2


    but you need to be sure your ram can handle the tight 2 or 2.5 settings
     

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